Nitrous Oxide Flashcards Preview

Inhaled Anesthetics > Nitrous Oxide > Flashcards

Flashcards in Nitrous Oxide Deck (20)
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1
Q

N2O boiling point

A

-88.5 C

2
Q

N2O saturated vapor pressure

A

38,628 mmHg

3
Q

N2O MAC

A

105 vol%

4
Q

N2O blood/gas coefficient

A

0.47

5
Q

N2O brain/blood coefficient

A

1.1

6
Q

N2O muscle/blood coefficient

A

1.2

7
Q

N2O fat/blood coefficient

A

2.3

8
Q

N2O Respiratory effects

A

Least decrease in tidal volume & increase in end tidal CO2 out of gases (Minimal compared to potent agents)
Reduces ventilatory response to hypoxia & hypercapnia
Additive respiratory depressant with other agents

9
Q

N2O CV effects

A

Direct negative inotrope
No substantial effect on LV diastolic function
Slight decrease in CO
Modest increase in pulmonary & systemic arterial pressure (increase arterial vasomotor tone) via a sympathomimetic effect - counteracts hypotensive effects of all other agents
Increases circulating norepi levels

10
Q

N2O Obstetrical effects

A

decreases activity of methionine synthetase & thymidylate synthetase - important for RNA/DNA replication - has been linked with miscarriages if N2O inappropriately scavenged

11
Q

N2O Discovery

A

1760s

12
Q

How does N2O effect MAC of other anesthetics

A

Each 1 vol% added to inspired gases, 1 vol% less potent inhalation agent may be administered

13
Q

N2O concentration effect

A

Leaves less space in FRC for fresh gas inflow to occur- as fresh gas saturated with anesthetic flows in the concentration of anesthesia in FRC increases faster

14
Q

N2O second gas effect

A

Not a big deal with sevo/des. Potent inhalation agent rises to higher concentration more quickly because of concentration effect.

15
Q

N2O Diffusion Hypoxia

A

N2O washes out fast due to coefficients, as N2O rushes into lungs to leave, it drags other gases with it & displaces O2 which can results in diffusion hypoxia. (just turn on oxygen, should be fine)

16
Q

N2O CNS effects

A

Inconsistent data - believed to increase CBP so increase ICP & CMRO2. May be attenuated by hypocapnia
Decreases seizure activity

17
Q

N2O renal effects

A

Decreases renal blood flow, GFR & urinary output

18
Q

N2O Complications

A

Contraindicated in patients with tympanic membrane/ear surgeries (*tympanoplasties), pneumothoraces (will double in size in 10 minutes, triple in 30 minutes), small bowel obstructions, pneumocephalus, air emboli (increase in pressure in spaces that cannot increase in size, increase in volume in spaces that can increase in size)

19
Q

NIOSH standards of N2O in ambient OR air

A

<25 ppm

20
Q

N2O liver:blood coefficient

A

0.8